32 On Diptera from Vera Cruz. 
brownish or pale. Claws and pulvilli elongate. Tegule 
large, translucent smoky-yellowish, halteres yellow. 
?. Differs in front being about one fourth width of head, 
frontal stripe and orbital margins in consequence narrower, 
the silvery of orbits with less of a golden sheen; wings not 
so broadened or large, evenly fuscous hyaline, without patch 
of dark fuscous on costa. Abdomen without purplish reflec- 
tion, shining black or with slight greenish reflection, the 
brassy-ashy pollen much more conspicuous, forming more or 
less distinctly a pair of triangular spots on anterior part of 
second, third, and fourth segments, leaving the median vitta 
apparent. The pollen varies in its intensity and shade of 
brassy. It is, together with the thoracic vitte, sometimes 
obscure and indistinct in both sexes. Foot-claws and pulvilli 
moderately short, about as long as last tarsal joint. 
Although these two forms (male and female) are in general 
facies so different, the fact that they were all taken together 
over the ants, without a single specimen of any other Hyalo- 
myia being present, one series being all males while the other 
is all females, convinces me that they are the two sexes of 
one species. 
It seems probable, from the circumstances under which this 
Hyalomyia was found, that it also, as well as the Stylogasters, 
is parasitic on ants (genus Lezton). In all my collecting 
in this locality, I met with no other specimens of [yalomyia 
than the above, excepting only the single specimen next 
described. 
i) r . ° 
35. Hyalomyia violascens, sp. 0. 
One male, San Rafael, June 26. 
Length 43 millim. 
Belongs in the group with punctigera, Towns., purpur- 
ascens, ‘lowns., &c., in which the front is trigonal, the eyes 
of male moderately or closely approximated, and those of 
female nearly or quite contiguous. Differs from my de- 
scription of purpurascens, g (Pr. Ent. Soc. Wash. i. p. 137), 
as tollows:—Orbits silvery pollinose, face subsilvery ; eyes 
closely approximated in front of ocelli, nearly obliterating the 
narrow brownish frontal vitta, which is thus elongate- 
triangular in front and narrowed to a line behind. Frontal 
bristles weak. Antenne black, third joint oval, a little 
longer and wider than first, silvery in some lights. Palpi 
very small, filiform, brownish. Thorax silvery only on 
humeri and pleure. The apical pair of scutellar bristles 
decussate. Abdomen wholly very polished deep violet- 
black, reticulations of the ashy pollen showing faintly in 
— Ss Fo 
